1. Field of the Invention
The present invention relates generally to pressure relief panel assemblies, and more particularly, to low pressure venting panels for preventing dangerous pressure build-ups in enclosures.
2. Description or the Prior Art
Pressure relief panel assemblies, sometimes referred to as explosion panels, have been developed and utilized heretofore. Such pressure relief panel assemblies are used to provide instantaneous low pressure relief to enclosures, such as tanks, food processing vessels, bag houses and the like, which are subject to rapid fluid pressure build-ups. For example, due to the collection of dust in bag houses, there is a constant risk of explosion. In order to prevent such explosions from causing severe damage to the bag house enclosure, equipment and personnel, one or more pressure relief panel assemblies are connected thereto which instantaneously rupture at relatively low pressures and provide large pressure relief openings through which pressurized burning gases are vented.
Pressure relief panel assemblies for preventing damage in the event of rapid pressure build-ups caused by explosions or other events have heretofore included composite rupture panels, i.e., panels made up of a number of parts which must rupture or open when pressurized fluid is relieved therethrough. For example, U.S. Pat. No. 4,498,261 issued Feb. 12, 1985 discloses a low pressure venting panel comprised of a rupture member having a plurality of slits and aperatures therein and a sealing membrane bonded to one side thereof. Both the rupture member and sealing membrane must rupture before opening of the panel is achieved.
U.S. Pat. No. 4,821,909 issued Apr. 18, 1989, another pressure relief assembly which utilizes a composite rupture panel, discloses a pressure relief panel comprised of a stainless steel member having slots which form lines of weakness therein and a sheet of plastic material bonded to one side of the stainless steel member.
Such prior composite rupture panels have tendencies to rupture at pressure differentials higher than expected in situations where extremely rapid pressure rises occur, e.g., an explosion. That is, because more than one part of the composite panel must rupture in order for the panel to open, the pressures required to rupture the individual parts can be additive rather than only that pressure which is required to rupture the strongest part.
In a number of applications, pressure relief panels are subjected to pressure-vacuum cycles, some as often as two or three cycles per minute. Such pressure-vacuum cycles cause the panels to flex which in turn often rapidly deteriorates composite panels causing them to fail prematurely.
Thus, there is a need for an improved pressure relief panel assembly comprised of a single rupture panel which reliably ruptures and opens at a predetermined pressure differential, and which can withstand pressure-vacuum cycles without premature deterioration or other adverse effect.